Date of Award
Department or Program
Biochemistry and Cell Biology
Chlamydomonas reinhardtii, a unicellular member of the Chlorophyta or Green Algae phylum, has been used for decades as a model for ciliary studies. Using this tool, previous work from our lab found a role for actin in ciliary assembly and maintenance. However, while the microtubule-based, membrane-ensheathed cilia of Chlamydomonas are highly conserved in relation to mammalian cells, the actin cytoskeleton is not as simple. Chlamydomonas contains two actin genes: IDA5, a conventional actin, and NAP1, a divergent actin. Here, we find that despite the divergence of NAP1, it is still able to interact with the actin nucleator, the Arp2/3 complex. We take advantage of this interaction to further dissect the role of actin in ciliary assembly and maintenance, as focusing on actin networks nucleated by a single actin nucleator allows us to look at a subset of the filamentous actin in this cell instead. By doing this, we are able to uncover a novel trafficking pathway for ciliary material where proteins and membranes are reclaimed from a pool in the cell body plasma membrane through Arp2/3 complex- dependent endocytosis. This trafficking pathway is important for ciliary assembly from zero length, ciliary maintenance, and ciliary elongation in the presence of lithium.
Bigge, B.M., Avasthi, P., 2022. Lithium-induced ciliary lengthening sparks Arp2/3 complex-dependent endocytosis. bioRxiv 2022.04.18.488674. https://doi.org/10.1101/2022.04.18.488674
Bigge, B.M., Rosenthal, N.E., Sept, D., Schroeder, C.M., Avasthi, P., 2020. Initial ciliary assembly in Chlamydomonas requires Arp2/3-dependent recruitment from a ciliary protein reservoir in the plasma membrane. bioRxiv 2020.11.24.396002. https://doi.org/10.1101/2020.11.24.396002
Craig, E.W., Mueller, D.M., Bigge, B.M., Schaffer, M., Engel, B.D., Avasthi, P., 2019. The elusive actin cytoskeleton of a green alga expressing both conventional and divergent actins. Mol. Biol. Cell mbc.E19-03-0141. https://doi.org/10.1091/mbc.E19-03-0141Zhang N, Pazouki L, Nguyen H, Jacobshagen S, Bigge BM, Xia M, Mattoon EM, Klebanovych A, Sorkin M, Nusinow DA, Avasthi P, Czymmek KJ, Zhang R. Comparative Phenotyping of Two Commonly Used Chlamydomonas reinhardtii Background Strains: CC-1690 (21gr) and CC-5325 (The CLiP Mutant Library Background). Plants (Basel). 2022 Feb 22;11(5):585. doi: 10.3390/plants11050585. PMID: 35270055; PMCID: PMC8912731.
Bigge, Brae M., "Novel functions for Arp2/3 complex-mediated actin networks discovered in Chlamydomonas reinhardtii" (2022). Dartmouth College Ph.D Dissertations. 109.